1. Field of the Invention
This invention relates to a water repellent adhesive composition for wooden material which consists of a particular paraffin emulsion and a resin component such as urea resin, urea-melamine resin, or phenol resin. More particularly, the invention is concerned with a single liquid type adhesive composition which is excellent in blendability and storage stability, and, moreover, is capable of imparting high degree of water-repellent property to the wooden material to be joined together.
2. Description of the Prior Art
There have so far been known, as the adhesive agent for wooden material, various resins such as urea resin, urea-melamine resin, phenol resin, and so on. Wooden materials such as particle board, fiber board, etc. obtained by using such adhesive agent, however, cannot be said to have sufficient water-resistant property, hence their utility has been fairly limited. With a view to pushing through this impasse, there has been proposed co-use of a water-repellency imparting agent such as paraffin emulsion, and so forth. However, when the conventional paraffin emulsion is mixed beforehand with an adhesive agent such as urea resin, etc. to prepare a single liquid type water-repellent adhesive composition, there takes place a segregation phenomenon in the mixture in several hours, or in a few days at the longest, which renders the blending stability of the mixture to be extremely poor. Such instability would also bring about a problem of non-uniformity in the water-repellent property in the wooden material as joined. To avoid such problem, therefore, it has so far been an established practice to adopt a method, in which, at the time of applying or coating the adhesive agent on wooden pieces, wood cuttings fiber dusts, chips, etc., the paraffin emulsion is additionally added or applied to these materials. Accordingly, in the course of manufacturing the wooden materials, the adhesive agent and the water-repellent agent should be stored in separate storage vessels for each of them, which leaves a problem in rationalization of the manufacturing steps.